UG 



1045 1045 



OPERATING EQUIPMENT 

FOR 

U.S. ARMY OBSERVATION BALLOONS 

TENSION METERS 
MANEUVERING BLOCKS 
MANEUVERING SPIDERS 
DANGER CONES AND CLAMPS 
VALVE TESTING DEVICE 
SAND BAGS 



PREPARED IN THE OFFICE OF THE 
CHIEF OF AIR SERVICE 



November, 1920 



^Ax^2)-V^ 




WASHINGTON 
GOVERNMENT PRINTING OFFICE 

1921 



Wak Department 

Document No. 1045 

Offlce of The Adjutant General 



kliflARY OF CONQJ^ESS 

\ eeeuMgNTs d. vision 



g 






WAR DEPARTMENT, 

Washington, November ^4? ^920. 
The following publication, entitled " Operating Equipment for 
U. S. Army Observation Balloons, Tension Meters, Maneuvering 
Blocks, Maneuvering Spiders, Danger Cones and Clamps, Valve 
Testing Device, Sand Bags," is published for the information and 
guidance of all concerned. 

[062.1, A. CO.] 

By order of the Secretary of War : 

PEYTON C. MARCH, 

Major General, Chief of Staff. 
Official : ' 

P. C. HARRIS, 

7' he Adjutant General. 



OPERATING EQUIPMENT FOR ARMY OBSERVATION BALLOONS. 



TENSION METERS. 

In order to safeguard the observation balloon from damage due 
to high winds and also to protect the cable from excessive strains it 
is necessary to frequently measure the tension to which the cable is 
subjected. 

There are two ways of obtaining this tension. First, the tension 
indicating device is built directly into the winch and is so arranged 
that the load on the cable is constantly indicated. If it is desirable, 
a registering device can be used, and thereby a graphic record of the 
tension throughout the flight is obtained for future use. However, 
this latter feature has not been deemed necessary in the United States 
Army Air Service. 

Second, a portable tension meter is also in use. This weighs between 
6 and 7 pounds ; is temporarily applied to the cable close to the winch ; 
a reading is taken and noted. The general principles of the tension 
meters are shown in figure 1. The cable is made to pass under three 
rollers, R, R', and R". The roller R is placed midway between the 
two rollers R' and R", so as to deflect the cable. This places a 
resultant pressure (W) against the roller R in the direction shown 
by the arrow. In the spring-type tension meter this pressure on 
roller R is resisted by means of a coil spring (see Plate I, fig. 2). 
The greater the tension on the coil the more this spring must be com- 
pressed in order to balance the thrust (W) on the roller. The com- 
pression of the spring is indicated hj graduations on the container by 
means of which the tensions in kilograms are indicated. 

The pressure (W) in the roller R in the direction of the arrow 
(Plate I, fig. 1) is 

2 T COS. a. 

If the angle (a) remains constant, the pressure (W) is in direct pro- 
portion to the tension (T). In the French tension meter the plunger 
supporting the roller has a mark which must at all times coincide 
with a fixed mark on the frame. This insures a constant angle (a). 
The spring pressure is regulated by means of a handwheel on the 
upper end of the plunger stem. It is obvious that if the tension 
changes while the instrument is in place the spring must be read- 
justed in order to bring the plunger back to position. This type of 
meter was used extensively by both the French and American armies 
in France. 

Another type of spring-pressure tension is shown in Plate I, fig. 3. 
In this instrument there are no adjustments to be made after the in- 

5 



6 OPERATING EQUIPMENT FOR ARMY OBSERVATION BALLOONS. 

strument is once placed on the cable. Any fluctuation in tension is 
immediately indicated by the movement of the plunger ; however, in 
this case the angle (a) varies. At (0) tension this angle is at its 
greatest. 

A spring as a measuring device, however, will not give complete 
accuracy. Two springs made at the same time from the same stock 
and hardened simultaneously may have a variance of 5 per cent. 
This could be overcome to a certain extent by graduating each indi- 
vidual meter to suit its particular spring. Should the spring become 




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FiiiATB I. — Diagrams showing principles of Tension Meters. 

broken and it could not be replaced by another having exactly the 
same characteristics, the tension meter would be beyond repair. As a 
compromise, all meters are graduated alike and a variation in read- 
ings from the true tension of at least 5 per cent is to be expected. 

In order to overcome the inaccuracies of a spring-type tension 
meter the Burton hydraulic meter has been designed. The principle 
is shown in Plate II, iigs. 4 and 5. Oil is practically noncompressible. 
Therefore when contained in an elastic tube thoroughly sealed, one 



OPERATING EQUIPMENT FOR ARMY OBSERVATION BALLOONS. 7 

end attached to a gauge as shown, any pressure applied against the 
lower end of the tube will cause practically no motion, but the oil 
will be placed in a state of hydraulic pressure which is in direct pro- 
portion to the load applied by the plunger. In other words, a load 
on the center plunger will cause the hydraulic pressure of the oil to 
register on the gauge. The pressure of the cable follows the rules as 
shown on figure 1 — that is, the angle (a) remains constant with a 
resultant pressure on the center pulley in direct proportion to the 
tension on the cable. The design of the tension meter is such that 
100-pound tension on the cable will cause a resisting hydraulic pres- 
sure of the fluid of 20 pounds per square inch. Two hundred pounds 
tension will give a hydraulic pressure of 40 pounds, and so on. The 
gauge, however, is graduated to read the tension directly. That is. 




FIGURE 4- 

Platb II.- — Burton Hydraulic Tension Meter. 

instead of showing an actual pressure of 20 pounds per square inch, 
the gauge dial is graduated to show 100 pounds, which corresponds 
to the cable tension. This tension meter is used in the following 
manner : 

If the diameter of the cable is not known, it should be measured. 

Turn the knurled screw "A" (Plate II, fig. 4) until the puUey " R " 
is backed into the frame, then place the tension meter on the cable as 
shown. 

Turn screw "A" until the indicating line " C " coincides with the 
correct graduation on the scale plate " D." These graduations repre- 
sent the cable diameter. Plate II, fig. 5 shows the position of the in- 
dicating line " C " wlien the tension meter is adjusted on a ^-inch 
diameter cable. The cable tension in pounds can now be read directly 
on the gauge. 



8 OPERATING EQUIPMENT FOR ARMY OBSERVATION BALLOONS. 

The screw " E " is for calibrating the instrument and must not he 
touched. Never remove the gauge from the instrument. 

DIRECTIONS FOR USE OF TYPE "E" TENSION METER. 

[French : For tensions from 60 to 1,200 kilograms. One kilogram =' 2.2 pounds.] 

Two cases should be considered : 

First case. — The diameter of the cable and rope is known. 

ADJUSTMENT OF THE INSTRUMENT. 

Move the sliding scale " C " with the milled screw " N " so as to 
bring the edge " B " against the figure of the scale " M " correspond- 




FIGURE. <o 

Pl.\te II. — -Burton Hydraulic Tension Meter. 

ing to the diameter of the cable. (The plate shows the correct adjust- 
ment for a cable of 11 mm.) 

MEASUMNG THE TENSION. 

Place the instrument on the cable as shown in the figure. Tighten 
the nut " V " until the line " K " is opposite the figure " 1 " on scale 
" C." Kun the instrument up and down the cable to make sure that 
the measurement is correct. Bead the scale " G " opposite the notch 
" R," the tension on the cable in kilograms. If the tension is higher 
than 600 kilograms bring the mark " K " opposite the figure " 2 " of 
the sliding scale and double the reading given on scale " G." If the 
tension is lower than 300 kilograms, the reading may be taken as 
follows : 



OPERATING EQUIPMENT FOR ARMY OBSERVATION BALLOONS, 9 

Bring the line " K " opposite the figure " i " on the sliding scale. 
Halve the reading given on scale " G." 

Second ca^e.— The diameter of the cable is not known. 




MEASURING THE DIAMETER OF THE CABLE. 

Unscrew the milled head " V " sufficiently for the cable placed in 
the grooves "A" and " B " not to touch the inner groove " E." Push 
the gliding rod " D " so as to bring the wheel " E " in contact with 
21933—21 2 



10 OPERATING EQUIPMENT FOR ARMY OBSERVATION BALLOONS. 



/I Orooi/ed iv/iee/s 

B £clffe on .sca/e 

C Sliding scale 

D Ol/din^ rod 

6 Scale 

H Frame 

K L me on scale 

M Scale 

N Screw 

/f A/otch 

lif Milled head 




T£NS/ON METER 

Type C. 




f^ORT/IBLf: T£:NS /ON METER 



PliATB III. — Vlewa showing construction of French type E, and a modification of the 
French type of portable meter. 



OPEEATING EQUIPMENT FOR ARMY OBSERVATION BALLOONS. 11 



the cable. This pulley must touch the cable but not press against 
it. Move the scale " C " by turning the screw " N " so as to bring the 








4- 
SO 




TENS /ON M£:t£:r Ty^^F-P. i '- ^/ 



n Iq 

Plate IV. — Views showing appearance and construction of tension meters installed 
directly on U. S. Army balloon winches. 

line " K " on to rod opposite the line " O " on the scale. The edge 
" B " will then be opposite the figure corresponding to the diameter 
of the cable in millimeters on scale " N." 



12 OPERATING EQUIPMENT FOR ARMY OBSERVATION BALLOONS. 
MEAStmiNG THE TENSION. 

The tension will then be measured as in the first case. 

Note. — (1) Make sure that the rod " B " glides easily on its bear- 
ings; oil if necessary. (2) When using the instrument always hold it 
by the flanges, never hold it either by the handle or by the milled 
head " V." (3) The instrument must be held so as to keep the rod 
" L> " horizontal. (4) The instrument is accurate to about one- 
twentieth of the reading. 

MANEUVERING BLOCKS. 

DESCRIPTION AND USE OF. 

The maneuvering block or sheave is a pulley constructed in such a 
manner that it may be opened and placed upon the balloon cable while 




Plate V. — Photograph of maneuvering blocks. 

the balloon is in ascension. It is generally used in connection with 
a maneuvering spider to haul down the balloon, if for any reason it 
becomes necessary, as for instance, when the winch becomes inopera- 
tive. If it becomes desirable that the balloon ascend from some other 
point than the winch site the maneuvering block is passed around the 
cable and is anchored at the desired point. In maneuvering across 
country innumerable conditions present themselves where the maneu- 
vering block is made use of. These conditions will not be presented 
here as they are fully covered in instruction manuals on maneuvering. 
There are three different models of maneuvering blocks illustrated 
herewith which present the types most used by the Army Balloon 
Service. They are all built to withstand stresses of from 10,000 to 
14,000 pounds. The workmanship is of the very best for the purpose ; 
all parts are buffed and polished. All blocks are constructed mostly 
of bronze, of the following composition : Eighty per cent copper, 10 
per cent phosphorus tin, and 10 per cent lead. 



OPERATING EQUIPMENT FOR ARMY OBSERVATION BALLOONS. 13 





M/INEC/l^^/?/A/G SLOC/r 



Plate V.— Standard types of maneuvering blocks used during war by U. S. Army. 



14 OPERATING EQUIPMENT FOE ARMY OBSERVATION BALLOONS. 

The sheave wheel is highly polished in the groove which is deep to 
keep the cable from flattening. The groove is designed to fit the cable 




Plate VI. — Burton maneuvering block (improved type). 
(Open.) 

snugly, but not tightly enough to cause wear on the sides of the cable ;. 
care should be exercised to avoid any rough spots in the groove, as 



OPERATING EQUIPMENT FOE ARMY OBSERVATION BALLOONS. 15 



there is no quicker way to destroy a cable than to have a rough sheave 
groove. One of the blocks shown is provided with a compression 
grease cup. This makes a good sheave for use where the sheave is 




Plate VI. 



-Burton maneuvering block (improved type). 
(Closed.) 



anchored, as high speed is developed requiring proper lubrication. 
For ordinary maneuvering purposes this grease cup is not required, 
and is a disadvantage, as their stems are easily broken. It is ap- 



16 OPERATING EQUIPMENT FOR ARMY OBSERVATION BALLOONS. 




Plate VIII. — Standard type of maneuvering spider. 




'I'l^TB IX.— View showing maneuvering blocli attached to cable and anchored to ground 
by anchorage spider. Note the screw pickets at the ends of the spider cables. 



OPEEATING EQUIPMENT FOR ARMY OBSERVATION BALLOONS. 17 

parent from the cuts how each type opens for placing on the cable. 
The very best of care should be accorded the maneuvering block, much 
depending upon its proper operation and strength when required, as 
it is under emergency conditions that its use is most often necessary-. 




MANEUVERING SPIDER. 

DESCRIPTION AND USE OF. 



The maneuvering spider is made up in various forms, two of the 
most common being illustrated herewith. Its purpose is to provide 



18 OPERATING EQUIPMENT FOR ARMY OBSERVATION BALLOONS. 

means for the men to apply their force to the maneuvering block, 
also to provide a ring from which to suspend sandbags to overcome 
the vertical component of the forces acting upon the maneuvering 
block when in use with the spider in hauling down balloons. 

Any rope with a loop spliced into the end, and of length sufficient 
to allow the required number of men to distribute themselves along 
same, will serve the purpose. However, under most conditions the 
types shown will be found most convenient, due to the men being able 



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to apply their force more directly to the maneuvering block, espe- 
cially where the ground is uneven. The size rope used is usually 1 
inch in diameter, this size giving sufficient strength when in good 
condition and being of cross section sufficient to afford the men good 
hand hold. The spliced loop at the block should be of ample length 
to accommodate all the sandbags, required to be attached thereto 
without necessitating some of the bags being hooked onto the ropes 
of other sandbags. When this practice has to be resorted to, the 



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— 1 



Soncf bo(fS 



bags not only are strained, but some hang low and drag upon the 
ground a great part of the time, thus causing inconvenience to men 
and a rapid destruction of the sandbags. 



DANGER CONES AND CLAMPS. 



DESCRIPTION OF. 



The rule is to attach danger cones to all captive balloon cables, 
starting about 800 feet below the balloon, with additional ones as 



OPEKATING EQUIPMENT FOR ARMY OBSERVATION BALLOONS. 19 



needed, placed about 300 feet apart. Experiments have been made 
with many types of clamping devices for attaching danger cones to 




MOD/r/Cy^T/ON or CL^Mf' 
Plate X. — Danger cone and clamps. 



balloon cables. To be satisfactory, any device of this kind must be 
easily attached and detached without stopping or slowing the winch. 



20 OPERATING EQUIPMENT FOR ARMY OBSERVATIOX BALLOONS. 

One type of clamp which has proved most satisfactory is a small 
stick of wood with slot and holes cut as shown by the sketch here- 
with. The danger cone and attaching devices illustrated are of 
standard design. The rope used is soft laid manila line. The cloth 
cone is composed of 12 segments of oil-print cotton, every other 
segment to be red, making three white panels of 2 segments each and 
3 red panels of 2 segments each. Top of cone has a three-eighth-inch 
diameter rope ring, 39 inches inside diameter, inserted in a pocket 
made of 8-ounce white Army duck. The suspension is made of three 
continuous ropes {^ inch in diameter) equally spaced around the top; 
where these connect to rope ring a three-eighth-inch brass grommet is 
inserted and the suspension ropes wrapped and spliced into them. 
At the point of meeting of these ropes a swivel snap is used for at- 
taching the cone to the cable clamp. The cloth is lock stitched (not 
cable stitched) at all seams. 

CARE AND USE. 

Danger cones should never be allowed to come in contact with the 
grease of the cable, and if through unavoidable circumstances grease 
or dirt has adhered to the cone it should be removed upon return to 
the hangar with gasoline or other suitable solvent. When not in 
use danger cones should be neatly folded and kept dry, and if in 
storage they must be aired and inspected frequently to avoid deterio- 
ration. The men whose duty it is to attach and detach these cones 
should be held responsible for the condition of the attaching devices 
as well as the cones themselves. Attaching devices and cones can 
be manipulated by a skillful soldier so that the winc-h never has to 
slacken speed for their attaching and detaching. If the cable is so 
overloaded with oil that the attaching device will not cling but slips 
(the cone becoming daubed with grease), it is not the fault of the 
attaching device, but of improper cable lubrication (see cables for 
lubrication). 

The grooves of the attaching devices illustrated are wedge shaped, 
tending to present a tight, narrow surface of contact with the cable. 
When in proper condition, either of the two devices shown will serve 
their purpose very satisfactorily. If the contact surfaces of these 
devices become smooth and worn, a file or a knife, with a few min- 
utes' work, will remedy the fault. 

VALVE-TESTING DEVICE. 

1. For testing valves where a very complete and accurate deter- 
mination is not required, the device shown in the illustration is very 
useful. It consists of two bags of two-ply standard envelope fabric, 
the larger 5 feet long by 22 inches in diameter, the smaller 2 feet 



OPEEATI^-G EQUIPMENT FOR ARMY OBSERVATION BALLOONS. 21 

long by IS inclies in diameter. Both of these bags are closed at one 
end the other ends being fitted with gasket seats made to clamp 
into the valve ring as shown in cut. The large bag is equipped with 
two nipples, one for the purpose of filling the bag and keeping the 
pressure up during test, the other for attaching a manometer ^ube 




The small bag has no openings except the one for the acceptance of 
the valve being tested. 

• ^' w ^'''!/'. '^^^''^ ""'^^ *^'^' "^^''^^^ ^^*^^ assembling as illustrated 
m cut (small bag not shown) the large bag is inflated to any desired 
pressure. During the test it may be necessary to put in more ^as 



22 OPERATING EQUIPMENT FOR ARMY OBSERVATION BALLOONS. 

because of contraction or loss of gas in case the large bag should not 
be absolutely gas tight. This can be determined by watching the 
manometer. If the valve seat is leaking the escaping gas will be 
caught by the small bag. If the small bag is still empty after a 
48-hour test, the valve may be considered in good condition. This 
testing device can be easily constructed by any balloon company with 
materials at hand. It is simple of construction and of use. 

SANDBAGS. 

In the illustration below the construction of a standard United 
States Army sandbag is shown. This bag is made of heavy brown 



a- "3 a/ij)ss 6ifo/r/fns Sfv^uy 











/-/ITT '2^ 
Platk XII. — Construction of U. S. Army Standard Hand Bag. 

duck of two ply on the bottom, section and single ply above. The 
method of construction is clearly shown, with over-all dimensions, 
stitching, attaching rope, hook, etc. Sandbags receive severe han- 
dling from the nature of work they are required to perform. Gen- 
erally about 33 pounds of sand are placed in each, but at times as 
high as 50 pounds is used and the capacity of the bag is such as to 
-accommodate this additional weight. The revised equipment table 
for one balloon company provides for 150 sandbags. Care should be 
taken never to allow moisture to collect in the sand used in these 
bags, as it causes a more rapid deterioration of the duck at normal 
temperature than when dry sand is used, and in freezing weather 
bags filled with moist sand are easily torn and damaged. 



o 



LIBRARY OF CONGRESS 




